The present invention pertains to revolvers, and in particular to revolvers of the gas seal type. Typically, in today's revolvers, the cylinder is made with a plurality of cartridge chambers and is rotatably mounted so that the chambers may be successively aligned with the barrel bore for firing. This two-part construction of the firing passage presents two major problems These are: the opportunity for propellant gas leakage at the junction between the barrel bore and the cylinder chamber, and the requirement for precise alignment between the barrel bore and the cylinder chamber at the moment of firing. If the cylinder chamber is not aligned precisely behind the barrel bore, so that the projectile may move unhindered from the chamber to the bore, the projectile can be shaved or deformed in its attempt to escape out the bore during firing. Also, dangerously high chamber pressure can result if the projectile's journey from chamber to bore is interfered with or inhibited due to non-alignment between chamber and bore. If propellant gas is allowed to escape between the cylinder chamber and barrel bore, the projectile suffers a loss in velocity and becomes less effective.
One solution which has been developed to alleviate gas leakage is the provision of a gas seal located between the barrel and the cylinder. The seal usually is formed by providing an annular ridge about the barrel bore and opposing countersinks about each chamber. Prior to the time of firing, the cylinder is typically pressed forwardly against the barrel so that the ridge is matingly received within the directly opposing countersink. Although, one design, the Iverson turret revolver, did operate the gas seal by moving the barrel back into contact with a cylinder consisting of chambers radiating out from a central point and all lying in a single plane. In any event, the mating engagement, then, effectively prevents any substantial loss of gases between the barrel and cylinder and also forces the cylinder into alignment with the bore. However, past gas seal revolvers have entailed complicated and/or cumbersome mechanisms for pressing the cylinder forwardly upon firing.
Gas seal revolvers, as with all revolvers, require the frequent loading of cartridges into the chambers and frequent cleaning of the revolver's operative parts to ensure its proper functioning. One effective design, aimed at easing the loading and cleaning operations, has been the tip-open construction, such as disclosed in U.S. Pat. No. 4,539,771 issued to Sirkis, Sept. 10, 1985. In a tip-open revolver, the barrel and cylinder assembly are pivotally mounted to the frame, so that the revolver may be split open to expose the rearward face of the cylinder and many operative parts for easy loading and cleaning procedures. Yet, tip-open revolvers have invariably entailed additional latch structures for fastening the pivotal parts together, and thereby increase the revolver's complication and susceptibility to disrepair. Moreover, no gas seal revolvers have been developed which utilize the advantageous tip-open construction.
An additional difficulty encountered in the manufacture of revolvers involves the indexing mechanism. The indexing mechanism rotates the cylinder in predetermined increments to thereby successively align the chambers of the cylinder with the barrel bore. Traditionally, a driving pawl is provided to cooperate with a circular ratchet which is fixedly mounted to the rearward face of the cylinder about its central axis. The ratchet is relatively small and is spaced radially inwardly from the chambers. This arrangement, therefore, requires very precise machining, since a small deviation in the ratchet's position translates into a magnified deviation for the chamber. Any deviation of the chamber's position from true alignment with the barrel bore must be avoided, otherwise the projectile will be shaved, deformed, etc., which significantly disturbs the projectile's velocity and accuracy of its flight and can increase chamber pressure dangerously.
In an effort to alleviate this problem, several suggested solutions have focused on engaging the cylinder along its outer periphery (beyond the chambers), such as seen in U.S. Pat. Nos. 4,581,835 to Brouthers et.al., 1,077,135 to Guerrero and 213,221 to Mauser. All these arrangements, however, present complicated and structurally weak arrangements for accomplishing the desired purpose. Hence, such structures are expensive to manufacture and have shortened life potential due to their susceptibility to disrepair.